1. Field of the Invention
This invention relates to improvements in ball and socket joints, particularly in the making of such joints of the type having a ball portion which cannot be assembled within the socket, other than by cutting slots in the socket.
2. Description of the Prior Art
The prior art on which this invention improves is illustrated in FIGS. 1 and 2 of the attached drawing. A ball and socket joint is formed of a ball 10 and a socket 12, the socket being machined on the end of a link 14. An arm 16 is machined to be attachable in a bushing portion 18 of the socket. The link and arm are useful in a number of applications, including actuators on guided missiles. The ball 10 is molded of suitable plastic material and includes a part spherical surface 20 and flat faces 22 as well as the drilled hole forming a bushing portion 18. The link 14 is formed of machinable metal and is drilled and machined to provide a socket hole 24 having a part spherical inner surface 26 matching the spherical surface of the ball 20. The link also has flat faces 28. In order to insert the ball 10 into the socket hole 24, it is further necessary to cut out portions 30 at diametrically opposite portions of the cylindrical surface 26 and of such a diameter that the ball can be turned sideways as shown in FIG. 2 inserted halfway into the socket and turned, in order to allow it to fit. The link 16 is then inserted into the ball placed within the socket, shown in FIG. 1, and secured. In order to have good bearing surfaces, the ball 10 of plastic must itself be machined. A typical plastic used is Delrin acetyl resin.
The disadvantages of the prior art include the fact that there is a burr left on the edges between the cylindrical surfaces 26 and the transverse cuts 30 and 32, and this burr increases friction and can cut into the plastic ball. Additionally, just forming the cuts 30 and 32 (called Messerschmett's in the trade) creates a complicated machining problem. Moreover, the space of the cuts 30 and 32 is space removed from the spherical bearing surface.